Accelerator position sensor arrangement structure for motorcycle

ABSTRACT

To provide an accelerator position sensor arrangement structure for a motorcycle that can prevent an increased vehicle-width without change of operational feeling of a throttle. An accelerator position sensor is connected to a throttle grip via a pair of throttle cables and disposed externally of main frames, of a body frame, extending from a head pipe toward the rearward of a vehicle body.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application is a divisional application of U.S. patentapplication Ser. No. 12/056,108 filed on Mar. 26, 2008, which claimspriority under 35 U.S.C. §119(a) on Patent Application Nos. 2007-090619and 2007-335752, filed in Japan on Mar. 30, 2007 and Dec. 27, 2007,respectively. The entirety of each of the above-identified applicationsis incorporated herein by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an accelerator position sensorarrangement structure for a motorcycle, wherein the operation of athrottle grip is detected by an accelerator position sensor and athrottle valve is driven by a control motor to control an amount ofintake air for an engine.

2. Background of the Invention

Examples of vehicles; namely, motorcycles include one in which athrottle grip and a throttle valve which controls an amount of intakeair for an engine are connected through a throttle wire and the throttlevalve is manually operated in response to throttle operation. In recentyears, there has been a vehicle in which the operation of a throttlegrip is detected by an accelerator position sensor and a throttle valveis driven by a control motor. In a motorcycle of this type, wherein thethrottle valve is driven by the motor, an accelerator position sensor isdisposed at one shaft end of the throttle valve in a throttle bodyconnected to an engine. Therefore, the accelerator position sensor isdisposed by the side of the throttle body (see Japanese Patent Laid-openNo. 2001-246960, for example).

In the configuration according to the background art, wherein thethrottle valve is driven by the motor, the throttle wire is connected toa position approximately equal to that of the vehicle with the throttlevalve that is manually operated. Therefore, the throttle wire can beextended in the same way, which offers approximately the sameoperational feeling of the throttle.

However, the accelerator position sensor is disposed by the side of thethrottle body. Therefore, a space is needed to dispose the sensor by theside of the throttle body. If the throttle body is disposed between apair of left and right main frames of a body frame, it is needed toexpand the gap between the main frames, which causes a problem ofincreased vehicle-width.

SUMMARY OF THE INVENTION

The present invention has been made in view of the foregoing andprovides an accelerator position sensor arrangement structure for amotorcycle that can prevent an increased vehicle-width.

To solve the above problem, the present invention is directed to anaccelerator position sensor arrangement structure for a motorcycle,wherein an accelerator position sensor detects operation of a throttlegrip and a control motor drives a throttle valve that controls an amountof intake air for an engine supported by a body frame, the acceleratorposition sensor is connected to the throttle grip via a throttle cable,and is disposed externally of main frames, of the body frame, extendingfrom a head pipe toward the rearward of a vehicle body.

According to the present invention, the accelerator position sensor isconnected to the throttle grip via the throttle cable and is disposedexternally of the main frames, of the body frame, extending from thehead pipe toward the rearward of the vehicle body. Thus, the acceleratorposition sensor can easily be disposed compared with the arrangement ofthe accelerator position sensor between the main frames and it ispossible to suppress an increase in vehicle-width without changing theoperating feeling of the throttle.

In this case, preferably, the main frames branch right and left from thehead pipe and extend toward the rearward of the vehicle body and theaccelerator position sensor is disposed externally of a vehicle bodyleft side main frame. With this configuration, the throttle cable can beextended to draw a gentle arc without an abrupt bend.

In this case, preferably, the throttle grip is provided on the rightside of a handlebar and the throttle cable extending from the throttlegrip is arranged to extend from the vicinity of the head pipe along theexternal lateral surface of the vehicle body left side main frame and isconnected to the accelerator position sensor. With this configuration,the extending arrangement of the throttle cable is made to haveapproximately the same trajectory as in the configuration according tothe background art, wherein the throttle cable extending from thethrottle grip is directly connected to the throttle valve and is madeapproximately the same extending length as that of the one according tothe background art. This can make the operating feeling of the throttleapproximately the same as that of the one according to the backgroundart.

In this case, preferably, the motorcycle includes a transverse-mountedradiator disposed externally of the vehicle body left side main frame,and a side cover covering a vehicle body lateral portion including theradiator, the side cover has an appearance cover covering the radiatorfrom above so as to be exposed to the outside, and the acceleratorposition sensor is disposed between the appearance cover and theradiator. With this configuration, the space defined between thetransverse-mounted radiator and the appearance cover can effectively beused to dispose the accelerator position sensor and also adhesion ofdust or the like can be avoided.

The present invention is also directed to an accelerator position sensorarrangement structure for a motorcycle, wherein an accelerator positionsensor detects operation of a throttle grip and a control motor drives athrottle valve that controls an amount of intake air for an enginesupported by a body frame, the body frame includes a pair of right andleft main frames which extend rearward of the vehicle body from a headpipe; a pair of left and right down tubes that extend from the head pipedownwardly of a vehicle body and support an engine; and a connectionmember that connects a rear portion of the main frame with a lowerportion of the down tube; and an opening is provided which is surroundedby the main frame, the down tube and the connection member so as to opento a side of the vehicle body and the accelerator position sensorconnected to the throttle grip via a throttle cable is disposed in theopening.

According to the present invention, since the opening is provided thatis surrounded by the main frame, the down tube and the connection memberso as to open to a side of the vehicle body, and the acceleratorposition sensor connected to the throttle grip via a throttle cable isdisposed in the opening, it is possible to suppress an increase invehicle-width without changing an operation feeling of a throttle ascompared with a configuration in which the accelerator position sensoris disposed between the main frames.

In this case, preferably, the main frames, the down tubes and theconnection members are integrally formed by casting. With thisconfiguration, compared with the case where they are manufacturedseparately from each other, an operation for joining them is eliminatedand variations in the shapes of the openings adapted to receive anaccelerator position sensor disposed therein are reduced.

In this case, preferably, a transverse-mounted radiator disposed on theoutside of the main frames is disposed at a position overlapping theaccelerator position sensor as viewed from the side. With thisconfiguration, the accelerator position sensor can inconspicuously bedisposed in terms of external appearance.

In the present invention, the accelerator position sensor is connectedto the throttle grip via the throttle cable, and is disposed externallyof the main frames, of the body frame, extending from the head pipetoward the rearward of the vehicle body. Therefore, the acceleratorposition sensor can easily be arranged and an increase in vehicle widthcan be suppressed without changing the operating feeling of thethrottle.

The main frames branch right and left from the head pipe and extendtoward the rear of the vehicle body, and the accelerator position sensoris disposed externally of a vehicle body left side main frame.Therefore, the throttle cable can be extended to draw a gentle arcwithout an abrupt bend.

The throttle grip is provided on the right side of the handlebar, andthe throttle cable extending from the throttle grip is arranged toextend from the vicinity of the head pipe along the external lateralsurface of the vehicle body left side main frame and is connected to theaccelerator position sensor. Therefore, the operating feeling of thethrottle can be made approximately the same as that of the one accordingto the background art.

The motorcycle includes the transverse-mounted radiator disposedexternally of the vehicle body left side main frame and the covercovering a vehicle body lateral portion including the radiator, the sidecover has an appearance cover covering the radiator from above so as tobe exposed to the outside, and the accelerator position sensor isdisposed between the appearance cover and the radiator. Therefore, thespace defined between the transverse-mounted radiator and the appearancecover can effectively be used to dispose the accelerator position sensorand also adhesion of dust or the like can be avoided.

In the present invention, the opening is provided that is surrounded bythe main frame, the down tube and the connection member so as to open toa side of the vehicle body, and the accelerator position sensorconnected to the throttle grip via the throttle cable is disposed in theopening. Therefore, it is possible to suppress an increase invehicle-width without changing feeling operation of a throttle.

Since the main frames, the down tubes and the connection members areintegrally formed by casting, an operation for joining them iseliminated and variations in the shapes of the opening portions adaptedto receive the accelerator position sensor disposed therein are reduced.

The transverse-mounted radiator disposed on the outside of the mainframes is disposed at a position overlapping the accelerator positionsensor as viewed from the side. Therefore, exposing the acceleratorposition sensor to the outside can be avoided and the arrangementflexibility of the transverse-mounted radiator can be improved.

Further scope of applicability of the present invention will becomeapparent from the detailed description given hereinafter. However, itshould be understood that the detailed description and specificexamples, while indicating preferred embodiments of the invention, aregiven by way of illustration only, since various changes andmodifications within the spirit and scope of the invention will becomeapparent to those skilled in the art from this detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description given hereinbelow and the accompanying drawingswhich are given by way of illustration only, and thus are not limitativeof the present invention, and wherein:

FIG. 1 is a lateral view of a motorcycle according to an embodiment ofthe present invention;

FIG. 2 is a plan view of the motorcycle;

FIG. 3 is a front view of the motorcycle;

FIG. 4 is a rear view of the motorcycle;

FIG. 5 is a lateral view illustrating an engine along with theperipheral configuration thereof;

FIG. 6 is a plan view illustrating the engine along with the peripheralconfiguration thereof;

FIG. 7 is a perspective view illustrating an AP sensor along with theperipheral configuration thereof;

FIG. 8 is a perspective view illustrating the AP sensor along with theperipheral configuration thereof;

FIG. 9 is a lateral view of the AP sensor;

FIG. 10 is a block diagram illustrating a throttle control system;

FIG. 11 illustrates an AP sensor according to a second embodiment asviewed from the side of a body frame;

FIG. 12 illustrates the AP sensor as viewed from the rear side of thebody frame;

FIG. 13 illustrates the AP sensor as viewed from above the body frame;

FIG. 14 illustrates the AP sensor as viewed from the front side of avehicle body;

FIG. 15 illustrates the AP sensor as viewed from obliquely above; and

FIG. 16 is a lateral view illustrating the AP sensor together withperipheral configurations.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The present invention will now be described in detail with reference tothe accompanying drawings, wherein the same reference numerals will beused to identify the same or similar elements throughout the severalviews. It should be noted that the drawings should be viewed in thedirection of orientation of the reference numerals.

An embodiment of the present invention will hereinafter be describedwith reference to the accompanying drawings. It is to be noted that thedirections such as the front, the rear or back, the left, the right, theupside, the lower side and the like are described with respect to avehicle body.

First Embodiment

FIG. 1 is a lateral view of a motorcycle according to an embodiment ofthe present invention. FIG. 2 is a plan view of the motorcycle. FIG. 3is a front view of the motorcycle. FIG. 4 is a rear view of themotorcycle.

Referring to FIGS. 1 and 2, the motorcycle 10 includes a body frame 11.A pair of left and right front forks 13 are turnably supported by a headpipe 12 attached to the front end of the body frame 11. A steeringhandlebar 15 is attached to a top bridge 14 supporting the upper end ofthe front fork 13. A front wheel 16 is rotatably supported by the frontfork 13. The motorcycle 10 further includes an engine 17 supported bythe body frame 11. An exhaust muffler 18 is connected to the engine 17via an exhaust pipe (not shown). A rear fork 20 is swingably supportedup and down by a pivot 19 located at the rear-lower portion of the bodyframe 11. A rear wheel 21 is rotatably supported by the rear end of therear fork 20. Rear cushions (not shown) are disposed between the rearfork and the body frame 11.

The body frame 11 includes a pair of right and left main frames 24 thatbranch right and left from the head pipe 12 and extend rearward andobliquely downwardly. A pair of left and right pivot plates 25 areconnected respectively to the rear portions of the main frames 24. Apair of left and right seat rails 26 extend rearward and obliquelyupwardly from front and rear portions of the pivot plates 25. The engine17 is supported below the main frames 24 and a fuel tank 22 is supportedabove the main frames 24. An occupant's seat 23 is mounted on the upperportion of the seat rails 26 and a grab rail 30 and a trunk box 27 aremounted to the rear portion of the seat rail 26.

The occupant's seat 23 includes a front seat 23A that extends rearwardof the fuel tank 22 and on which a rider sits. A rear seat 23B is formedrearward of the front seat 23A to be raised and on which a pillionpassenger sits. A pillion passenger's backrest 23C is supported on therear seat 23B. The pivot plate 25 of the body frame 11 is attached witha pair of left and right steps (the rider's foot-placed steps 28 for arider sitting on the front seat 23A), and with a pair of left and rightsteps (pillion passenger's foot-placed steps) 29 for the pillionpassenger sitting on the rear seat 23B. The grab rail 30 to be grabbedby the pillion passenger, a main stand 31, a sub stand 32, a bodycowling 40 described later, etc. are attached to the body frame 11.

The body cowling 40 includes a front fairing 41 covering the vehiclebody from the front. A pair of left and right side covers 42 covers thelateral portions of the vehicle body. An under cover 43 covers the lowerportion of the vehicle body. A rear seat cowl 44 covers the rear portionof the vehicle body. A front fender 46 is attached to the front fender46 so as to cover the front wheel 16. A pair of left and rightsaddlebags 45 are formed integrally with the rear seat cowl 44. A rearfender 47 is attached to the seat cowl 44 so as to cover the rear wheel21. The front fairing 41 and the pair of left and right side covers 42may be formed integrally with each other.

Referring to FIG. 3, headlights 50 are provided on the front surface ofthe front fairing 41 and a windscreen (wind shield) 51 is attached abovethe headlights. Left and right mirrors 53 each incorporating a frontblinker are respectively provided at the left and right ends of thefront fairing 41. As shown in FIG. 2, vehicle meters 55 are disposedinside of the front fairing 41.

As shown in FIG. 3, the side covers 42 are respectively provided with apair of left and right air openings 42A adapted to supply outside airfrom the front of the vehicle to the surrounding of the engine 17. Anengine guard 56 is provided left-forward of and right-forward of theengine 17 and a pair of left and right fog lamp 57 are attached to theengine guard 56.

As shown in FIG. 2, a pair of left and right side upper covers(appearance covers) 42B are attached to the respective side covers 42 soas to cover between each of the side covers 42 and a corresponding oneof the main frames 24 and to be exposed to the outside. The side uppercovers 42B block flow of heat warmed by the engine 17 through the gapseach between the side cover 42 and the body frame 11. The side uppercover 42B also functions as a decorative cover that covers the radiator67 (FIG. 5), described later, from above.

Referring to FIG. 4, a pair of left and right tail lamp units 60 isarranged on the rear surface of the trunk box 27 and rear blinkers 61are respectively arranged on the rear surfaces of the saddle bags 45. Arod antenna 58 is attached to the right-hand portion of the trunk box 27in order to be used when an audio unit (not shown) incorporated in themotorcycle 10 receives radio broadcasting.

FIG. 5 illustrates both the engine 17 and its peripheral configurationand FIG. 6 is a plan view of FIG. 5. The engine 17 is ahorizontally-opposed 6-cylinder engine in which three cylinders lined inthe back and forth direction of the vehicle body are provided on eachside, namely, on each of the left and right sides. Referring to FIG. 5,the engine 17 is carried by the main frames 24 and by the pivot plates25. An intake manifold 17A is joined to the engine 17 from above and anair cleaner (not shown) is connected from above to the intake manifold17A via a throttle body 63.

Referring to FIG. 6, the throttle body 63 has a pair of left and rightintake passages 63A. Butterfly-type throttle valves 63B are supported bythe respective intake passages 63A so as to have a common valve shaft63C extending in the width-direction of the vehicle body and to controlthe respective opening degrees for controlling an amount of air intakefor the engine 17.

An actuator 65 that receives therein a control motor 64 turnably drivingthe valve shaft 63C is disposed at one end (at the right-hand end of thevehicle body) of the valve shaft 63C. The actuator 65 and the throttlebody 63 are disposed between the pair of left and right main frames 24.The actuator 65 supports the control motor 64 so that the rotationalaxis of the control motor 64 may be parallel to the valve shaft 63C. Inaddition, the actuator 65 constitutes an electric throttle mechanismwhich transmits the rotation of the control motor 64 to the valve shaft63C via a reduction gear mechanism.

The engine 17 is a water-cooled engine and an radiator 67 is provided tocool the cooling water of the engine 17. As shown in FIG. 5, theradiator 67 is a transverse-mounted radiator transversely secured, fromoutside, to the front end of the left-hand main frame 24. A blast fan67A is integrally attached to the radiator 67 so as to forcibly pass airthrough the radiator 67. An accelerator positioning sensor (hereinaftercalled the AP sensor) is disposed on the left-hand main frame 24 at aposition above the radiator 67 so as to detect the operation of athrottle grip 15A (see FIG. 2) provided on the right side of thehandlebar 15.

The AP sensor 100 will hereinafter be described with reference to FIGS.7 to 9. The AP sensor 100 is disposed outside the vehicle body left sidemain frame 24 and above the radiator 67 via a bracket 101 which issecured at one end to the main frame 24 with screws 101A and 101B.Consequently, in the state where the body cowling 40 is attached, the APsensor 100 is received in the space between the radiator 67 and the sideupper cover 42B (FIG. 2) covering between the side cover 42 and the mainframe 24.

As shown in FIGS. 7 and 8, the AP sensor 100 has a sensor support plate102 secured to the bracket 101 with the screws 101A and 101B. A throttledrum 110 is turnably mounted to the sensor support plate (sensor body)102. Two throttle cables 115 and 125 pulled out from the throttle grip15A are connected to the throttle drum 110. One throttle cable 115functions as an opening-side throttle cable that is pulled in responseto the opening-side turning of the throttle grip 15A. The other throttlecable 125 functions as a closing-side throttle cable that is pulled inresponse to the closing-side turning of the throttle grip 15A.

More specifically, the throttle cables 115 and 125 use respective pushcables in which inner cables 115B and 125B are movably inserted intoouter cables 115A and 125A, respectively, as shown in FIG. 9.

The throttle cables 115 and 125 extend from the throttle grip 15A towardthe vicinity of the head pipe 12, and thereafter as shown in FIG. 8,extend along the external lateral surface of the vehicle body left sidemain frame 24. The respective ends of the outer cables 115A and 125A arefixedly supported by a cable support plate 103 formed at the front endof the sensor support plate 102.

As shown in FIG. 9, the inner cable 115B pulled out from the outer cable115A of the opening-side throttle cable 115 is wound on the outercircumference of the throttle drum 110 while an engaging piece 115Cprovided at one end of the inner cable 115B is engaged with the throttledrum 110. The winding direction of the opening-side throttle cable 115is set in a direction where the throttle drum is turnably driven in anopening direction M indicated with an arrow in FIG. 9 during a pull.

The inner cable 125B pulled out from the outer cable 125A of theclosing-side throttle cable 125 is wound on the outer circumference ofthe throttle drum 110 while the engaging piece 125C provided at one endof the inner cable 125B is engaged with the throttle drum 110. Thewinding direction of the closing-side throttle cable 125 is set in adirection where the throttle drum 110 is turnably driven in a closingdirection N indicated with an arrow in FIG. 9 during a pull.

The throttle drum 110 includes a turning disk 111 around which thethrottle cables 115 and 125 are wound. The turning disk 111 is supportedturnably around a shaft 111A and biased to turn in the closing directionN by a return spring 112, a torsion spring.

With such a configuration, when the throttle grip 15A is opened, theturning disk 111 is turned in the opening direction M against thebiasing force of the return spring 112. When the throttle grip 15A isreturned, the turning disk 111 is turned in the closing direction N bythe biasing force of the return spring 112.

A throttle operation amount sensor 130 is connected to a surface (thesurface on the external side of a vehicle body) of the sensor supportplate 102 opposed to the throttle drum 110. The throttle operationamount sensor 130 detects a turning amount of the turning disk 111 ofthe throttle drum 110, thereby detecting an operation amount of thethrottle grip 15A, namely, a rider's throttle operation amount.

A connector 130A of the throttle operation amount sensor 130 isconnected to an electronic control unit (ECU) 200 for controlling thevarious parts of the motorcycle 10. The throttle operation amountdetected by the throttle operation amount sensor 130 is notified to theelectronic control unit 200.

FIG. 10 is a block diagram illustrating a throttle control system. Theelectronic control unit 200 is a device that centrally controls thevarious parts of the vehicle body. In the throttle control, theelectronic control unit 200 drives the control motor 64 on the basis ofa throttle operation amount detected by the throttle operation amountsensor 130 to drive the throttle valve 63B, thereby controlling throttleopening.

The electronic control unit 200 receives respective signals outputtedfrom a throttle opening sensor 210 for detecting the opening degree ofthe throttle valve 63B, from a vehicle-speed sensor 220 for detectingvehicle-speed, from an intake air pressure sensor 230 for detectingpressure of intake air for the engine 17, and from an intake airtemperature sensor 240 for detecting intake air temperature. On thebasis of the detection results of such sensors, the electronic controlunit 200 appropriately corrects and controls the throttle opening degreeso that a rider may obtain acceleration or deceleration that meets heror his expectation by throttle operation.

As described above, the motorcycle 10 of the present embodiment has theAP sensor 100, which is disposed externally of and close to the vehiclebody left side main frame 24. Therefore, it is not necessary to disposethe AP sensor between the main frames 24. This makes it easy to assembleor remove the AP sensor as compared with the AP sensor disposed betweenthe main frames 24 according to the background art. In addition, thedistance between the main frames 24 can be reduced to suppress anincrease in vehicle-width. The distance between the main frames 24 canbe reduced to provide effects that lowering of foot-groundingperformance of an occupant mounting on the motorcycle 10 can be avoidedand that the capacity of the radiator 67 disposed externally of the mainframe 24 can sufficiently be ensured.

In the present configuration, the throttle cables 115 and 125 extendingfrom the throttle grip 15A on the right side handlebar 15 are arrangedto extend along the outside of the vehicle body left side main frame 24.Thus, the throttle cables 115 and 125 can be arranged to extend withoutan abrupt bend, while drawing a gentle arc. This extending arrangementprovides approximately the same trajectory as in the configuration ofthe throttle manual-operation according to the background art, whereinthe throttle cable extending from the throttle grip is directlyconnected to the throttle valve and also can make the throttle cableapproximately the same extending length as that of the one according tothe background art.

More specifically, in the configuration of the throttlemanual-operation, the throttle cable extending from the throttle grip isextended to the vicinity of the head pipe 12, then passed below the mainframes 24, and extended to the throttle body 63. However, theconfiguration of the present embodiment provides approximately the sameextending arrangement as a case where the background art arrangement ofthe throttle cable extending from the vicinity of the head pipe 12 andpassing below the main frames 24 is changed to approximately horizontalextending arrangement. Thus, it is possible to make the operatingfeeling of the throttle almost the same as the one according to thebackground art. Even if the AP sensor 100 is disposed, it is possible tosuppress an increase in vehicle-width without changing the operatingfeeling of the throttle.

In the present configuration, the AP sensor 100 is disposed in theexisting unused space defined between the transverse-mounted radiator 67and the side upper cover 42B (FIG. 2) covering between the side cover 42and the main frame 24. Therefore, it is not necessary to newly providean arrangement space for the AP sensor 100 and it is possible to avoidadhesion of dust or the like. Also in this configuration, a maintenanceoperator (owner or the like) can easily access the AP sensor 100 byremoving the side upper cover 42 or by removing an opening/closing lidprovided above the AP sensor in the side upper cover 42B. This makes itpossible to easily perform work such as grease injection, componentreplacement and the like.

Second Embodiment

FIG. 11 illustrates an AP sensor 100 according to a second embodiment ofthe present invention as viewed from the side of a body frame 11. In thepresent embodiment, configurations approximately identical to those inthe first embodiment are identified with like reference numerals andtheir detailed explanations are omitted.

Referring to FIG. 11, a body frame 11 includes a pair of right and leftmain frames 24 that branch right and left from a head pipe 12 and extendrearward and obliquely downwardly. A pair of left and right down tubes71 extend from the head pipe 12 downwardly of a vehicle body and supportan engine 17. A pair of left and right connection members (tensionpipes) 72 each connects a corresponding one of the rear portions of themain frames 24 with a corresponding associated one of the lower portionsof the down tubes 71. The main frames 24, the down tubes 71 and theconnection members 72 are integrally formed by casting. In FIG. 11,reference numeral 87 identifies an air cleaner disposed between the mainframes 24.

The main frame 24 is provided such that a main frame front end portion24A located forward of a join portion with the connection member 72 isformed thinner than a main frame intermediate portion 24B as viewed fromthe side. In addition, the upper surface of the main frame front endportion 24A slants rearward downward so as to smoothly merge with theupper surface of the main frame intermediate portion 24B so that thehead pipe 12 is connected with the main frame intermediate portion 24B.The connection member 72 extends from the down tube 71 obliquely andrearward upwardly at a portion below the main frame front end portion24A and connects with the main frame intermediate portion 24B. In thisway, the main frame front end portion 24A, the connection member 72 andthe down tube 71 are almost triangularly assembled to enhance the framerigidity of the front portion of the body frame 11. In addition, a pairof left and right opening portions 81 is each formed almost triangularlyon the side of the front portion of the body frame 11.

In this configuration, the AP sensor 100 for detecting the operation ofa throttle grip 15A (FIG. 2) provided on the right side of the handlebar15 is disposed in the opening portion 81 opening to the left side of thefront portion of the body frame 11. More properly, upwardly projectingboss portions 82 and 83 are formed integrally with the connection member72 so as to be spaced apart from each other in the back and forthdirection. The AP sensor 100 is brought into contact with the inside ofthe boss portions 82 and 83 and secured to the boss portions 82 and 83with bolts 85 and 86 inserted into the boss portions 82 and 83,respectively, from the outside (the vehicle body widthwise outside)thereof.

FIG. 12 illustrates the AP sensor 100 as viewed from the rear side ofthe body frame 11. FIG. 13 illustrates the AP sensor 100 as viewed fromabove the body frame 11. FIG. 14 illustrates the AP sensor 100 as viewedfrom the front side of the vehicle body. FIG. 15 illustrates the APsensor 100 as viewed from obliquely above. As shown in FIGS. 12 and 13,the almost entire AP sensor 100 is accommodated in the opening portion81 except for a connector 130A.

More specifically, as shown in FIGS. 11 and 12, the AP sensor 100includes a sensor body 150 joined to the boss portions 82 and 83; and acable support plate portion 160 holding respective outer cables 115A and125A of the two throttle cables 115 and 125 pulled out from the throttlegrip 15A. Since the cable support plate portion 160 is located on thefront side of the sensor body 150, the AP sensor 100 is formed so thatit can approximately be accommodated in the width of the main frame 24and the back-and-forth length of the AP sensor 100 can be accommodatedin the back-and-forth length of the opening portion 81.

The cable support plate portion 160 includes cable joint portions 160Aand 160B (FIG. 11) that are vertically spaced apart from each other andextend toward the front of the vehicle body. As shown in FIG. 13, sincethe main frame 24 bends toward the head pipe 12 as viewed from above inthe vicinity of the cable joint portions 160A and 160B, the throttlecables 115 and 125 (outer cables 115A and 125A) can be arranged toextend from the head pipe 12 along the left main frame 24 withoutoccurrence of an abrupt bend and almost without contact with the mainframe 24.

As shown in FIG. 11, a throttle drum 110 with which the throttle cables115 and 125 are connected is turnably supported by the sensor body 150outwardly of the vehicle body. More specifically, the inner cable 115Bof the throttle cable 115 which is an opening-side throttle cable iswound from above around the throttle drum 110 and an engaging piece 115Cprovided at one end of the inner cable 115B is engaged with the throttledrum 110. In addition, the inner cable 125B of the throttle cable 125which is a closing-side throttle cable is wound from below around thethrottle drum 110 and an engaging piece 125C provided at one end of theinner cable 125B is engaged with the throttle drum 110. The throttledrum 110 is turnably biased to the closing side (clockwise in FIG. 11)of the throttle grip 15A by a return spring 112 (not shown).

With such a configuration, if the throttle grip 15A is opened, thethrottle drum 110 is turned to the opening side (counterclockwise inFIG. 11) against the biasing force of the return spring 112. If thethrottle grip 15A is returned, the throttle drum 110 is turned to theclosing side against the biasing force of the return spring 112.

As shown in FIG. 12, a throttle operation amount sensor 130 fordetecting the turning amount of the throttle drum 110 is provided on thesensor body 150 inwardly of the vehicle body.

As shown in FIGS. 12 and 13, the connector 130A of the throttleoperation amount sensor 130 projects from the opening portion 81inwardly of the vehicle body toward downward of the vehicle body. Acable arranged to extend from an electronic control unit (ECU) 200 (notshown) for controlling various portions of the motorcycle 10 isconnected from below to the connector 130A. The throttle operationamount detected by the throttle operation amount sensor 130 is notifiedto the electronic control unit 200, which drives a motor to control thethrottle opening.

In the present embodiment, a transverse-mounted radiator 67 is disposedoutwardly of the front end portion of the main frame 24 as shown in FIG.13. In this arrangement layout, the transverse-mounted radiator 67 isdisposed at a position overlapping, as viewed from the side, the APsensor disposed in the opening portion 81 in the front portion of thebody frame 11 as shown in FIG. 16. Thus, the AP sensor 100 cannot beseen from the outside because of the radiator 67, that is, the AP sensor100 can inconspicuously be arranged in terms of external appearance.

A radiator cover 67B is disposed inwardly of the radiator 67 withrespect to the vehicle body. A radiator grill 67G is disposed outwardlyof the radiator 67 with respect to the vehicle body. The radiator cover67B functions as a cooling air introducing box. In addition, theradiator cover 67B is concave toward the inside of the vehicle body andclose to the main frame 24 and is formed, by integral molding, with anopening portion 67C (FIGS. 14 and 15) provided with a lattice-like grillon the front side of the cover. This makes it possible to introduce therunning air from the front of the vehicle body, into the inside of thecover 67B from the opening portion 67C thus the running air passesthrough the radiator 67. If a radiator fan 67A (FIG. 5) of the radiator67 is rotated during parking or the like, air passing through theradiator 67 is blown toward the front of the vehicle body via theopening portion 67C.

A wall of the radiator cover 67B inward of the vehicle body is formedwith a concave portion 67D concave along the throttle cables 115 and125. This concave portion 67D avoids the interference between theradiator cover 67B and the throttle cables 115 and 125.

As described above, in the motorcycle 10 of the present embodiment, theAP sensor 100 is disposed in the opening portion 81 surrounded by themain frame 24, the down tube 71 and the connection member 72 and openingto the side of the vehicle body. Thus, the distance between the mainframes 24 can be reduced compared with that of a background artmotorcycle in which the AP sensor is disposed between the main frames.This can suppress an increase in vehicle-width. In addition, a situationcan be avoided where the AP sensor 100 limits the arrangement of thetransverse-mounted radiator 67 located outwardly of the main frames 24.

The throttle cables 115 and 125 extending from the throttle grip 15A onthe right side of the handlebar 15 are arranged to extend along theoutside of the vehicle body left side main frame 24 and connected withthe AP sensor 100. Thus, the throttle cables 115 and 125 can be arrangedto extend without an abrupt bend, while drawing a gentle arc. Thisextending arrangement can be made approximately the same as in theconfiguration of the background art throttle manual-operation in whichthe throttle cable extending from the throttle grip is directlyconnected to the throttle valve and can make the operating feeling ofthe throttle almost the same as the one according to the background art.In short, even if the AP sensor 100 is disposed, it is possible tosuppress an increase in vehicle-width without changing the operatingfeeling of the throttle.

In the configuration, since the AP sensor 100 is disposed in theexisting opening portion 81 that is formed as a result of increasing therigidity of the body frame 11, it is not necessary to newly provide anarrangement space for the AP sensor 100. Thus, the existing unused spacecan effectively be used to increase space use efficiency.

Since the transverse-mounted radiator 67 disposed on the outside of themain frame 24 is disposed at a position overlapping the AP sensor 100 asviewed from the side, the AP sensor 100 can inconspicuously be disposedin terms of external appearance.

Since the main frames 24, the down tubes 71 and the connection members72 are integrally formed by casting, compared with the case where theyare manufactured separately from each other, a bonding operation iseliminated and variations in the shapes of the opening portions 81 arereduced. This can avoid situations or the like where the opening portion81 is machined for correction when the AP sensor 100 is disposed in theopening portion 81.

Since it is only needed to mount the AP sensor 100 from the outside ofthe vehicle body with the two bolts 85 and 86, the AP sensor 100 can bemounted and dismounted with ease.

The presence invention has been described based on the embodiment thusfar but is not limited to this embodiment. Various design changes can beperformed. For example, the embodiment describes the case where thepresent invention is applied to the accelerator position sensorarrangement structure for the motorcycle as described above. However,the invention is not limited to this but can widely be applied to theaccelerator position sensor arrangement structure for optionalmotorcycles such as scooter type vehicles.

The invention being thus described, it will be obvious that the same maybe varied in many ways. Such variations are not to be regarded as adeparture from the spirit and scope of the invention, and all suchmodifications as would be obvious to one skilled in the art are intendedto be included within the scope of the following claims.

1. An accelerator position sensor arrangement structure for amotorcycle, comprising: an accelerator position sensor adapted to detectoperation of a throttle grip; and a control motor adapted to drive athrottle valve which controls an amount of intake air for an enginesupported by a body frame, wherein the body frame includes a pair ofright and left main frames which extend toward a rear of a vehicle bodyfrom a head pipe; a pair of left and right down tubes which extend fromthe head pipe downwardly of the vehicle body and support an engine; anda connection member on at least one side of the motorcycle whichconnects a rear portion of the corresponding main frame with a lowerportion of the corresponding down tube; and wherein an opening foraccommodating the accelerator position sensor is provided which issurrounded by the main frame, the down tube, and the connection memberon the at least one side of the motorcycle so as to open to a side ofthe vehicle body, and a throttle drum of the accelerator position sensoris connected to the throttle grip via a pair of throttle cables, whereinthe throttle grip is provided on a right side of a handlebar, thethrottle cables extend downwardly and forwardly from the throttle grip,around a forward side of the head pipe, and rearwardly along an externallateral surface of the left main frame, to the throttle drum of theaccelerator position sensor on an outer side of the opening, wherein thethrottle drum is surrounded in a radial direction thereof by the mainframe, the down tube, and the connection member, thereby avoiding a needto increase a distance between the left and right main frames, andfurther comprising: a transverse-mounted radiator disposed on an outsideof the main frames and disposed at a position overlapping theaccelerator position sensor, so that when the motorcycle is viewed inside view, the accelerator position sensor is inconspicuously arrangedin terms of external appearance and cannot be seen, wherein the radiatorincludes a radiator cover disposed inwardly of the radiator with respectto the vehicle body, and the radiator cover is formed with a concaveportion concave which ensures that the radiator cover does not interferewith a portion of the throttle cables extending along the externallateral surface of the left main frame to the accelerator positionsensor.
 2. The accelerator position sensor arrangement structure for themotorcycle according to claim 1, wherein the main frames, the downtubes, and the connection members are integrally formed by casting. 3.The accelerator position sensor arrangement structure for the motorcycleaccording to claim 1, and further comprising: a throttle operationamount sensor which detects the position of the throttle drum, whereinthe throttle operation amount sensor extends inwardly from the openingin order to connect to an electronic control unit which controls variousparts of the motorcycle, wherein when the body frame is viewed fromabove, substantially all of the accelerator position sensor isaccommodated in the opening, except for a connector of the throttleoperation amount sensor, wherein the connector of the throttle operationamount sensor projects from the opening in an inward direction relativeto the body frame, the electronic control unit which controls variousparts of the motorcycle being connected to the connector of the throttleoperation amount sensor via a cable.
 4. An accelerator position sensorarrangement structure for a motorcycle, comprising: an acceleratorposition sensor adapted to detect operation of a throttle grip; and acontrol motor adapted to drive a throttle valve which controls an amountof intake air for an engine supported by a body frame, wherein the bodyframe includes a pair of right and left main frames which extend towarda rear of a vehicle body from a head pipe; a pair of left and right downtubes which extend from the head pipe downwardly of the vehicle body andsupport an engine; and a connection member on at least one side of themotorcycle which connects a rear portion of the corresponding main framewith a lower portion of the corresponding down tube; and wherein anopening is provided which is surrounded by the main frame, the downtube, and the connection member on the at least one side of themotorcycle so as to open to a side of the vehicle body, and whereinaccelerator position sensor is disposed in the opening and isaccommodated approximately in a width of the main frame, and aback-and-forth length of the accelerator position sensor is fullyaccommodated in the back-and-forth length of the opening, therebyavoiding a need to increase a distance between the left and right mainframes, and a throttle drum of the accelerator position sensor isconnected to the throttle grip via a pair of throttle cables, andfurther comprising: a transverse-mounted radiator disposed on an outsideof the main frames and disposed at a position overlapping theaccelerator position sensor, so that when the motorcycle is viewed inside view, the accelerator position sensor is inconspicuously arrangedin terms of external appearance and cannot be seen, wherein the radiatorincludes a radiator cover disposed inwardly of the radiator with respectto the vehicle body, and the radiator cover is formed with a concaveportion concave which ensures that the radiator cover does not interferewith a portion of the throttle cables extending along the externallateral surface of the left main frame to the accelerator positionsensor.
 5. The accelerator position sensor arrangement structure for themotorcycle according to claim 1, wherein the accelerator position sensoris mounted in the opening from outside of the body frame with boltsextending orthogonally with respect to the body frame.
 6. Theaccelerator position sensor arrangement structure for the motorcycleaccording to claim 2, wherein the accelerator position sensor is mountedin the opening from outside of the body frame with bolts extendingorthogonally with respect to the body frame.
 7. The accelerator positionsensor arrangement structure for the motorcycle according to claim 1,further comprising upwardly projecting boss portions formed integrallywith the connection member so as to be spaced apart from each other in aback and forth direction, wherein the accelerator position sensor isattached to an inside of the boss portions.
 8. The accelerator positionsensor arrangement structure for the motorcycle according to claim 1,wherein the accelerator position sensor disposed on the inner side ofthe opening is located above the engine.
 9. The accelerator positionsensor arrangement structure for the motorcycle according to claim 1,wherein the control unit and the throttle grip are located on the sameside of the motorcycle.
 10. The accelerator position sensor arrangementstructure for the motorcycle according to claim 3, wherein a front sideof the radiator cover includes an opening portion with a lattice grill,which makes it possible to introduce running air from a front of thevehicle body, into an inside of the radiator cover from the openingportion, and through the radiator.
 11. The accelerator position sensorarrangement structure for the motorcycle according to claim 4, whereinthe throttle grip is provided on a right side of a handlebar, and thethrottle cables extend downwardly and forwardly from the throttle grip,around a forward side of the head pipe, and rearwardly along an externallateral surface of the left main frame, to the throttle drum of theaccelerator position sensor on an outer side of the opening.
 12. Theaccelerator position sensor arrangement structure for the motorcycleaccording to claim 4, wherein a front side of the radiator coverincludes an opening portion with a lattice grill, which makes itpossible to introduce running air from a front of the vehicle body, intoan inside of the radiator cover from the opening portion, and throughthe radiator.
 13. The accelerator position sensor arrangement structurefor the motorcycle according to claim 4, wherein the acceleratorposition sensor disposed on the inner side of the opening is locatedabove the engine.
 14. The accelerator position sensor arrangementstructure for the motorcycle according to claim 4, wherein control unitand the throttle grip are located on the same side of the motorcycle.15. The accelerator position sensor arrangement structure for themotorcycle according to claim 1, wherein since the accelerator positionsensor is accommodated in the opening, rather than between the mainframes, a distance between the main frames can be reduced, therebysuppressing an increase in vehicle-width.
 16. The accelerator positionsensor arrangement structure for the motorcycle according to claim 4,wherein since the accelerator position sensor is disposed in theopening, rather than between the main frames, a distance between themain frames can be reduced, thereby suppressing an increase invehicle-width.